Recent Problem with NVIDIA GTX 260

Hi wish anyone could troubleshooting this annoying problem for me...
My pc was working fine without this problem, but i formated it and updated motherboard bios, windows update, nvidia drivers, flashplugins, video codecs i used before without any trouble.
And the problem started...

So what is happening now is surfing can cause a bit of delay when im trying to scroll pages up or down once in a while. or pc reacts by delays by simple click to open a new tab to browse.
Watching youtube videos was causing me nvidia stop working and has recovered.
So i did a chkdsk /f and that message stoped showing.
I watched a full AVI movie once in a while was doing some fast anoying stop and go "freezes"
When i start a game im obligated to do hard reset and remove cmos, doing that i also removed graphic card cleaned it up and started pc but the problem its still here somewhere.
btw im running default system without any OC's
Core i7
6GB
Windows7 64 like i was using before the problem started.
Nvidia Driver last one 340.52

Any ideas to fix this annoying freezes and pc crash?

Memtest the ram.

Memory its fine.
Last time i formated pc happen the same problem but it was ages ago i cant remenber what have i done to fix it had the same hardware tho.
I remenber it was something fixed with software related to nvidia.